Hydraulically operated tool

ABSTRACT

A HYDRAULICALLY OPERATED TOOL FOR PUNCHING HOLES IN METAL PLATES OR CRIMPING LUGS WHICH CONSIST OF A TOOL WITH A HAND OPERATED LEVER COUPLED TO A FLUID PRESSURE CREATING PUMP, SUCH THAT REPEATED OPERATION OF SAID LEVER GRADUALLY INCREASES THE PRESSURE CREATED BY SAID PUMP TO RETRACT A PISTON ROD INTO THE TOOL, THE OUTER END OF THE PISTON ROD PASSING THROUGH A STATIONARY DIE AND TERMINATING IN A REMOVABLE PUNCH, MOVABLE RELATIVE TO SAID DIE.

Feb. 23, 1971 W BURR0WS 3,564,716

HYDRAULICALLY OPERATED T09; v Filed May 17, 1968 y f2 sheets-sheet 1 Z VIII/1*k www-von WLUAM BU RROWS mm, 59mm) AYTORNES Feb. 23, 1971 u W, BRROWS W 'I HYDRAULICALLY OPERATED TOOL Filed may 1'?, 196e 2 sheets-.sheet z Z0 NVENTOR WILUAM EURROWSA BY:

ATTORNEYS Elfenv United States Patent O 3,564,716 HYDRAULICALLY OPERATED TOOL William Burrows, Burrows Brothers, Shelbourne Road, Brockhampton Lane, Havant, Hampshire, England Filed May 17, 1968, Ser. No. 730,062 Int. Cl. B26f 1 00 U.S. Cl. 30-360 3 Claims ABSTRACT OF THE DISCLOSURE A hydraulically operated tool for punching holes in metal plates or crimping lugs which consist of a tool with a hand operated lever coupled to a fluid pressure creating pump, such that repeated operation of said lever gradually increases the pressure created by said pump to retract a piston rod into the tool, the outer end of the piston rod passing through a stationary die and terminating in a removable punch, movable relative to said die.

Briefly, the present invention is concerned with a tool for carrying out operations such as punching holes in metal plates or crimping lugs for copper and aluminium alloy cables, and consists in a tool having a hand operable lever coupled to a iluid pressure creating pump such that repeated operation of said lever gradually increases the pressure created by said pump, the resulting pressure created by the pump being used to retract a piston rod into the tool, the outer end of the piston rod passing through a stationary die and terminating in a removable punch. VIn use the punch is removed from the piston rod and the piston rod is then passed through a hole in said plate or lug. Thereafter the punch is resecured to the protruding end of the piston rod and the hand operable lever ac* tuated to cause the punch to be drawn against or into said die to punch through the plate or crimp said lug.

The punch is releasably coupled to the piston rod to enable it to be replaced :by other punches of different sizes and/ or shape.

The die may also be adapted to be replaceable to enable a suitable die to be matched with a selected punch.

In operation, for example to punch a hole in a metal plate, a small hole is iirst formed in the plate by any conventional known means, thereafter the piston rod of the device, 'without the punch thereon, is passed through the hole in the plate from one side thereof so that said piston rod projects from the other side of the plate'and said die is on said one side of the plate, the punch is then secured to said projecting end of the piston rod, and thereafter the pump is operated to cause the punch to move towards the die to cause the plate to 4be sheared between the punch and the die. For this purpose, the punch and die are suitably shaped, for example, a :concave punch co-operating with a `flat die or vice versa.

In order that the invention may be clearly understood reference will now be made to one embodiment thereof as illustrated in the accompanying drawings, and Iwherein:

FIG. 1 is a side elevation, partly in crosssection of one embodiment of the present invention taken along the line A-A of lFIG. 2;

FIG. 2 is an end elevation of FIG. l looking in the direction C;

FIG. 3 is a view, partly in cross-section, taken along the line B-B of FIG. 2; and

FIG. 4 is a detail of a modied construction of an end fitting for the tool.

'Referring rst to FIG. 1 it will be seen that the tool comprises a cylindrical punch 1 having a threaded bore into which extends a screw-threaded end of a piston rod 2. 'Ihe piston rod 2 extends through a die 3 mounted on 3,564,716 Patented Feb. 23, 1971 ice one end of a cylinder 5 in which slides a piston 4. The piston 4 is intermediate the ends of the piston rod 2.

The cylinder housing 5 is provided lwith a pivot l6A on wh1ch is pivotally mounted a hand operable lever 6. The hand operable lever 6 is acted on by a return-spring 6B that tends to maintain the lever 6 in a forward setting. In the particular embodiment illustrated the hand lever 6 is of channel-shape so that the spring 6B has one end that nests within the channel, the other end of the spring 6B which is of vcoiled form, engages 'with a suitable part of the cylinder housing 5.

The cylinder housing 5 includes a pump-cylinder 9 in which a fluid pressure creating piston 7 is housed. Between the piston 7 and the lever 6 is a link 8 pivotally mounted at one end on the lever 6 and pivotally mounted at its other end on the piston 7.

The cylinder housing 5 includes flow-paths 10, 11 that lead to a first one-way ball valve 12 and thence to the left-hand side of the piston 4 as viewed in FIG. 1.

The end of the piston rod 2 remote from the punch 1 slides in an end housing 14 that closes the rear end of the cylinder housing 5. This end housing 14 includes a recess 15 that accommodates one end of a compression spring 16, the compression spring 16 surrounding the piston rod 2 and acting at its upper end against the piston 4. Thus the compression spring 16 tends to move the punch 1 away from the die 3. In the end housing 14 is a pump suction 4passage or inlet '17 that leads to a second oneway ball valve 18 housed in the cylinder housing 5, this second one-way ball valve 18 being at the junction of the llow paths 10 and 11. The pump suction passage or inlet 17 is also an anti-airlock device that effectively extends the pump inlet towards the centre of the cylinder to prevent air from ybeing dra-wn into the pump when the tool is used in an inverted position.

It will be seen from FIG. 1 that the front end of the cylinder housing 5 is of stepped formation as indicated at 19 in order that different sized dies 3 may be accommodated on said stepped formation according to the size of hole that is required to punch, the punch 1 being removable so that it may be replaced with a different die according to said size required.

Referring now to FIG. 3 it will be seen that the cylinder housing 5 also includes a return-flow path 20 that leads from the left-hand side of the volume swept out by the piston 4 as viewed in FIGS. 1 and 3, said return flow path 20 leading to the right-hand side of the bore in the cylindrical housing 5 as viewed in said figures. A needle valve 21 is associated with the return flow path 20 in order that said return flow path can be closed whilst the tool is being used to punch a hole.

The device described with reference to FIGS. l, 2 and 3 operates as follows.

The needle valve 21 is rst unscrewed to open up the return flowpath 20. This permits the compression spring 16 to push the piston 4 towards the die 3, the liquid displaced by this movement of the piston 4 passing along the return ilowpath 20 into that part of the cylinder housing 5 in which the compression spring 16 is situated. Thereafter the needle valve 21 is again closed.

A hole the size of the piston rod 2 is then drilled or otherwise formed in, for example, a metal plate that is to have a hole of a desired shape punched therein. The punch 1 is unscrewed from the piston rod 2 and the appropriate die 3 is placed on the stepped formation 19 of the cylinder 5.

The screw` threaded end of the piston rod 2 is then passed through said hole in the metal plate and the appropriate punch 1 is then screwed on to said threaded end of the piston rod 2.

The tool is then held in the hand and the lever 6 is repeatedly squeezed towards a hand grip 23. This movement of the lever 6 causes the piston 7 to reciprocate in the pump cylinder 9.

On each compressive stroke of the piston 7 the oneway ball valve 18 raises to seal off the inlet 17, and the pressurised liquid opens the one-way ball valve 12 to permit the pressurized liquid to enter the space 13 on the left-hand side of the piston 4 as viewed in FIG. 1. The piston 4 is thus displaced by an increment in a manner compressing the spring 16 and causing the punch 1 to move towards the die 3.

Each time the squeeze on the lever 6 is released, the spring 6B causes the piston 7 to retract to its initial setting. The resulting decrease in pressure in the pump cylinder 9 causes the rst one-way ball valve 12 to close, thus sealing H? the space 13 on the left-hand side of the piston 4; and the second one-way ball valve 18 to open, thus permitting liquid to pass into the pump cylinder 9 from that part of the cylinder housing that surrounds the compression spring 16.

The screw means 24 is used to limit the play of the second one-way ball valve 18.

FIG. 4 illustrates a detail of a modified construction of an end litting for the tool. In this embodiment the end housing 14 for the cylinder 5 has no provision for the piston rod 2 to extend therethrough. The end housing has, however, a screwed bore 25 into which is threaded a nipple 26 extending from an expandable bellows-type diaphragm 27. The bellows 27 are protected by an end cap 28 fitted on the end housing 14. The end housing 14 has an inlet 17 for the purpose described with reference to FIG. 1.

The bellows 27 serve to rapidly vary the effective volume of the cylinder housing 5 on the right-hand side of the piston 4, as used in FIG. 1 and thus serves to prevent air being inadvertently drawn into said left-hand side on release of the squeezed pressure on the hand operated lever 6.

Having now described one embodiment of the invention, and a modification of a detail thereof, it will be appreciated that these are by way of example only and that any modification may be made thereto.

In FIG. 1 the right-hand portion of the piston rod 2 need not extend through the end housing 14, the piston rod 2 on the right-hand side of the piston 4 being in the form of a small stub portion whose purpose is to centralise the compression spring 16 on the piston 4. It has been found that pressures up to 21/2 tons can be obtained by operating the tool with one hand only.

I claim:

1. A tool comprising a cylinder housing;

a reciprocal piston in said housing;

a piston rod on said piston axially displacable thereby and projecting from said housing;

a hollow die mounted on said housing axially of said piston rod which projects therethrough;

a punch removably mounted on said piston rod and movable thereby into said die;

the cylinder volume on one side of the piston acting as a liquid reservoir;

a flow path conduit in said housing interconnecting opposite ends of said cylinder;

a hand-operable pump mounted on said housing having an outlet connected to said conduit for drawing liquid from said reservoir and forcing it via said conduit into the cylinder volume on the other side of the piston to cause the piston rod to be drawn inwardly of said cylinder housing;

a first one-way valve (18) in said flow path conduit that is closed in response to the pressure set up on each compressive stroke of the hand operable pump, said first one-way valve preventing liquid being fed into said reservoir by the hand-operable pump, and and a second one-way valve (12) in said flow path conduit that opens in response to the pressure set up on each compressive stroke of the hand-operable pump to permit pressurized liquid from the pump to enter into the cylinder volume on said other side of the piston.

2. A tool as claimed in claim 1 and including an expandable bellows coupled to that part of the cylinder that acts as a reservoir.

3. A tool as claimed in claim 1 and including a second ow path conduit (20) interconnecting the two ends of the cylinder;

said second flow path conduit including a valve (21) such that said second ow path conduit can be closed during a punching operation and open thereafter to permit the punch to be moved away from the die.

References Cited UNITED STATES PATENTS 2,237,069 4/ 1941 Christenson 30-360 2,536,709 1/1951 Ashton 30-361 2,633,197 3/1953 Nischan '3G-360 2,714,250 8/1955 TWedt 30-228X 2,729,063 1/1956 Hoadley 81-301X 3,058,214 10/1962 Mekler 30-180 3,269,011 8/1966 Herrstrum 30360 ROBERT C. RIORDON, Primary Examiner J. C. PETERS, Assistant Examiner 

